Reflection properties of multimode interference devices

Abstract

Absh-nct-We report on the reflection properties of multimode interference (MMI) devices: we distinguish between reflection back into the input waveguides and internal resonance modes due to the occurrence of simultaneous self-images. Because of self-imaging, reflection CBn be extremely efficient, even in the case of MMI devices with optimized transmission. This conclusion is confirmed by the observed spectral behavior of InP-based ring lasers incorporating MMI 3dB couplers and MMI power splitters. Several techniques are proposed to minimize the influence of these reflections.

Experimental assessment of the reflection of passive multimode interference couplers

“…It is typically in the range from 45 to 50 dB (worst case 42 dB). The simulated MMI reflection is typically below 50 dB with a few worst case peaks remaining below the 40 dB level [3]. From the measurements it is confirmed that MMI-coupler reflections are less the 40 dB.…”

“…Particularly, multimode interference (MMI)-couplers that are intensively used in integrated optics devices can be expected to provide reflections since they contain abrupt junctions. The issue of MMI-coupler reflections in semiconductor lasers was addressed by Pennings et al [3]. The paper concentrates on the occurrence of resonant modes in the coupler.…”

“…The present work is concerned with the assessment of the reflections of passive MMI-couplers, including nonresonant conditions. The experimental results are compared with the simulated data from [3].…”

Ring Resonator Lasers using Passive Waveguides and Integrated Semiconductor Optical Amplifiers

“…A further improvement in performance of MMI coupled ring lasers, as suggested in [7] where completely active devices are presented, is by the use of a single active gain section in the ring, and making the MMI coupler and outcoupling waveguides of passive waveguide material as presented in this paper.…”

Multimode interference photonic switches

“…13 As a result of self-images, the possibility of achieving a crossover of strip guides, a simple 3-dB directional coupler, and a filter ͑separating two wavelengths͒ was demonstrated by Ulrich and Ankele, 14 but only since the early 1990s has the concept been studied in more detail. Key papers written by Soldano, Penning, et al 4,6,15 analyzed the mathematics of the self-imaging phenomenon by calculating the coupling coefficients and predicting where multiple images can be found. Another key paper by Bachmann et al 16 in 1994 took this theory even further to calculate the phase relation between the input and the outputs, and outputs relative to each other.…”